Such a plate-type heat exchanger is known, for example, from European Patent Publication EP 0 623 798 A1. This heat exchanger has a plurality of heat exchanger plates which are stacked on top of each other, so that their borders overlap at least partially. The individual heat exchanger plates are connected with each other in that the plate packages are soldered together in a vacuum furnace. In the process, the brazing material of the plated heat exchanger plates is melted, but the creation of embedded oxides cannot be ruled out. Furthermore, large overlapping areas in general have the disadvantage of having long degassing paths, so that gas could possibly be embedded during brazing. Large overlapping areas have the further disadvantage that component tolerances have a disadvantageous effect on the gap conditions, since possibly the optimal contact between the borders is no longer assured.
A plate-type heat exchanger is known from European Patent Publication EP 0 742 418 A2, in connection with which it has been attempted to overcome these disadvantages in that the plate bottom makes a transition via a shoulder into the border. If the individual heat exchanger plates are stacked on top of each other, the plate bottom of one heat exchanger plate rests on the shoulder of the adjoining lower heat exchanger plate, so that in this way overlapping areas are created, which have a relatively small surface, or respectively short degassing paths. The border adjoining the shoulder and projecting toward the outside is not important when brazing the individual heat exchanger plates together.
A plate-type heat exchanger is known from European Patent Publications EP 0 258 236 B1 and EP 0 551 545 A1, wherein the heat exchanger plates have a border which is alternatingly beveled several times, so that it has shoulder-like contact faces. As in European Patent Publication EP 0 742 418 A2, the plate bottoms of the adjoining heat exchanger plates are placed on these shoulders, so that a definite contact between two adjoining heat exchanger plates is assured.